Exam 3

In order for glycolysis to continue in the absence of cellular respiration with oxygen, which product must be regenerated?

NAD+

Under anaerobic conditions, glycolysis slows due to the depletion of:

NAD+

When a muscle is working strenuously and becomes anaerobic, pyruvate from glycolysis is reduced to lactate to allow the oxidation of ______ to ______

NADH to NAD+

anabolic/biosynthetic reaction

a chemical reaction in which small molecules are used to synthesize larger molecules

Bacteriorhodopsin

a light driven H+ pump found in archaea

ATP synthase functions like what?

a rotary machine; it spins

hydrolysis of ATP

a water molecule is added to ATP resulting in its breakdown to ADP and inorganic phosphate

electronegativity

ability to attract electrons in a chemical bond

Many of the proteins of the electron transport chain contain prosthetic groups. These prosthetic groups commonly contain iron, which can easily:

accept or release an electron

Ethanol production by yeast results when NADH donates its electrons to...

acetaldehyde

Krebs Cycle reactants

acetyl CoA and oxaloacetate

ATP

adenosine triphosphate; common energy source of cells; all cells use ATP to carry and release energy cyclically

anaerobic

an environment without oxygen

During strenuous exercise, what type of condition may develop in cells when the rate of oxygen delivery cannot keep up with the rate of oxygen demand?

anaerobic

What mechanisms have evolved to allow the metabolism of organic molecules in the absence of oxygen?

anaerobic respiration and fermentation

kinetic energy

associated with movement

The oxidation of NADH initially leads to a high concentration of protons in the:

intermembrane space

Glycolysis

involves the breakdown of one molecule of glucose into two molecules of pyruvate

what are the two general forms in which energy exists?

kinetic energy and potential energy

oxidation

loss of electrons

anaerobic respiration

metabolizes organic molecules in the absence of oxygen by using a substance other than O2 as the final electron acceptor of an electron transport chain

The matrix has a (blank) charge compared to the intermembrane space because positively charged protons are constantly pumped from the matrix to the intermembrane space

negative

chemical reaction

one or more substances are changed or converted into other substances

The final electron acceptor in the electron transport chain is:

oxygen

Some species of bacteria that live in anaerobic conditions have evolved specialized enzymes that work like cytochrome c to...

pass electrons to molecules other than O2

The purpose of the energy investment phase of glycolysis is to:

prime glucose for the exergonic reactions to follow

fermentation

produces ATP by substrate-level phosphorylation without any net oxidation of organic molecules

The energy released during the transfer of electrons in the electron transport chain is used to:

pump protons across the inner mitochondrial membrane

substrate

reactant of an enzyme-catalyzed reaction

The electron transport chain involves a series of

redox reactions

The final step in fermentation, leading to the production of lactate or ethanol, results from pyruvate or acetaldehyde being (blank) by NADH.

reduced

Muscle cells overcome the buildup of NADH and decrease of NAD+ under anaerobic conditions by...

reducing pyruvate to lactate

endergonic reaction

requires an input of energy; products have higher free energy that reactants; not spontaneous; have a positive change in free energy

potential energy

stored energy; associated with the position of an object

biochemistry

study of the chemistry of living things

Fermentation produces less ATP than aerobic respiration because during fermentation:

the NADH that is made during glycolysis is not used to make ATP by chemiosmosis

energy

the ability to promote change or do work

The second event in oxidative phosphorylation is the production of ATP by...

the enzyme ATP synthase

In E. coli, under anaerobic conditions, the production of a proton gradient is coupled to:

the reduction of nitrate to nitrite

During oxidative phosphorylation, ATP synthesis is coupled to:

the removal of high-energy electrons from NADH and FADH2

all the steps of glycolysis can be grouped into...

three phases

Enthalpy (H)

total energy of a system

spontaneous reaction

type of reaction or process that occurs without needing an input of energy

what form of energy can be used to drive cellular processes such as muscle contraction and cellular movements?

usable energy

When would E. coli use nitrate rather than oxygen as a final electron acceptor?

when oxygen is absent

chemical equilibrium

when the rate of formation of products equals the rate of formation of reactants

How do anaerobic conditions develop in cells?

when the rate of oxygen delivery cannot keep up with the rate of oxygen demand

exergonic reaction

will proceed without the input of energy; releases energy during product formation; spontaneous

glycolysis can take place...

with or without oxygen

energy investment phase

During this phase, two ATP molecules are used as reactants. ATP is hydrolyzed so that the phosphate groups can be added to glucose

Krebs Cycle products

- 1 GTP - 3 NADH - 1 FADH2 - 2 CO2 - regenerated oxaloacetate

What describes the three conformations of the β subunit of ATP synthase?

- ATP is released - ATP is bound - ADP and Pi are bound

Why does fermentation produce less ATP than aerobic respiration?

- Electrons in the NADH produced during glycolysis are not used to make ATP by chemiosmosis - The pyruvate produced during glycolysis is not oxidized to produce additional ATP

What problem results from the buildup of NADH and decrease of NAD+ under anaerobic conditions?

- High concentrations of NADH can lead to the release of free radicals, which can damage DNA and proteins -

What happens during the fermentation reactions that occur in muscle cells?

- Pyruvate is reduced to lactate - NADH is oxidized to NAD+

Aerobic respiration yields ______ ATP molecules per glucose, while fermentation typically yields ______ ATP molecules per glucose

34-38 ; 2

What is true regarding the generation of an electrochemical gradient during the conversion of nitrate to nitrite when nitrate serves as a final electron acceptor?

- Ubiquinone picks up H+ in the cytoplasm and carries it to the other side of the membrane - NADH dehydrogenase pumps H+ out of the cytoplasm - The reduction of nitrate to nitrite consumes H+ in the cytoplasm

metabolic pathway

- a coordinated series of chemical reactions in which each step is catalyzed by a specific enzyme - can result in the synthesis of larger molecules from smaller molecules - a different enzyme catalyzes each step - can result in the breakdown of large molecules - the product of one reaction becomes the substrate for the next reaction - categorized according to whether the sequence of coordinated chemical reactions leads to the breakdown or synthesis of substances

redox reaction

- an oxidation reaction paired with a reduction reaction - reduction= gain of electrons, reduction in charge (-) - oxidation= loss of electrons, gain in charge (+)

three levels of regulation of catabolic and anabolic pathways

- genetic - cellular - biochemical

What do I need to know about glycolysis?

- occurs in the cytoplasm - series of reactions that convert glucose (6-C) into 2 pyruvates (3-C) - 2 ATPs are initially expended to phosphorylate sugars - A net of 2 ADPs are eventually converted to ATP - 2 NAD+ are reduced to 2 NADH - steps are all catalyzed by enzymes - (do not need to know intermediates or enzymes that catalyze reactions)

Intermediate Step between glycolysis and Krebs Cycle

- pyruvate is transferred to mitochondrial matrix - pyruvate is oxidized by pyruvate dehydrogenase - pyruvate is left as an acetyl group, produces CO2 and NADH

the following can occur during a chemical reaction?

- rearrangement of atoms within molecules - molecules are broken apart - molecules attach to each other to form larger molecules - electrons are transferred between atoms

two main functions of catabolic pathways

- recycle components of macromolecules - produce energy intermediates, such as ATP, which are directly used to drive endergonic reactions in cells

The structural components of the electron transport chain include:

- small organic molecules - protein complexes

three energy intermediates for cellular respiration

ATP, NADH, FADH2

4 steps of cellular respiration

1. Glycolysis 2. Pyruvate processing 3. Citric acid cycle 4. Oxidative phosphorylation

Arrange the steps that occur when ATP synthase produces ATP in the correct order

1. Hydrogen ions flow through a channel in the membrane-bound subunits of ATP synthase 2. the y subunit of ATP synthase rotates in a clockwise direction 3. the β subunits of ATP synthase change confirmation 4. ATP is synthesized

cellular respiration order of processes

1. glycolysis 2. Intermediate step 3. Krebs (citric acid) Cycle 4. Oxidative Phosphorylation

electron transport chain (ETC)

A group of protein complexes and small organic molecules within the inner membranes of mitochondria and chloroplasts and the plasma membrane of prokaryotes; the components accept and donate electrons to each other in a linear manner and produce a H+ electrochemical gradient

Which of the following statements is true about all forms of anaerobic respiration?

A molecule other than O2 is used as the final electron acceptor

oxidative phosphorylation

A process during which NADH and FADH2 are oxidized to make more ATP via the phosphorylation of ADP

cleavage phase

A six-carbon molecule is converted to two three-carbon molecules

In different conformations, ATP synthase may be bound to (blank) and Pi, bound to ATP, or not bound to a nucleotide.

ADP

energy-liberation phase

ATP and NADH are synthesized; produces 4 ATP, 2 NADH, and two pyruvate molecules

ATP synthase

An enzyme that utilizes the energy stored in a H+ electrochemical gradient for the synthesis of ATP via chemiosmosis

As a result of the reactions of the citric acid cycle, the carbons from acetyl CoA are released as:

CO2

Fermentation that occurs in yeast cells is represented by the equation:

Glucose -----> 2 ethanol + 2 CO2 + 2 ATP

Which of the following equations represents the type of fermentation carried out in muscle cells?

Glucose -----> 2 lactate + 2 ATP

As electrons travel through the electron transport chain, (blank) ions are pumped across the cristae into the space between the inner and outer mitochondrial membranes, from a low concentration to a high concentration

H+

In aerobic respiration, O2 is reduced to what?

H2O

When electrons are transferred to oxygen in the final step of the electron transport chain, what molecule is produced

H2O

How is ATP produced during fermentation?

Substrate-level phosphorylation

Krebs (citric acid) Cycle

The citric acid cycle captures the energy stored in the chemical bonds of acetyl CoA (processed glucose) in a step-by-step process, trapping it in the form of high-energy intermediate molecules, then passes it on to oxidative phosphorylation

cellular respiration

The metabolic reactions that a cell uses to get energy from food molecules and release waste products

When will an endergonic and exergonic reaction that are coupled proceed spontaneously?

When the net free energy change for both reactions combined is negative (exergonic)

If an organism can use only O2 as a final electron acceptor, can it generate ATP under anaerobic conditions?

Yes, it can generate ATP through glycolysis

In yeast cells, fermentation regenerates NAD+ and produces which chemicals?

carbon dioxide and ethanol

products of cellular respiration

carbon dioxide, water, and ATP

cytochrome oxidase

catalyzes the transfer of electrons to O2 at the end of the electron transport chain

what bonds in glucose store large amounts of energy?

covalent bonds

what are the two main factors that determine the fate of a chemical reaction?

direction and rate

mitochondria

double-membraned organelle; Krebs Cycle occurs here

The flow of electrons through the electron transport chain is exergonic. Therefore...

electron flow occurs spontaneously and does NOT require an input of energy.

In the electron transport chain, electrons are transferred to molecules with increasingly higher:

electronegativity

free energy (G)

energy available to do work

three phases of glycolysis

energy investment, cleavage, energy liberation

The flow of electrons through the electron transport chain is:

exergonic

The breakdown of glucose to lactate or ethanol as a final end product is an example of what?

fermentation

The flow of protons through ATP synthase causes the ______ subunit to turn clockwise. This causes the three ______ subunits to change their conformations in a way that favors ATP synthesis and release.

γ ; β